Advance of technology makes LED lamps that generate greater brightness and provide longer life span widely adopted on traffic lights and indication lights of electric appliances. With growing awareness of energy saving and reducing carbon footprint, LED lamps become a main focus these day to displace the conventional fluorescent lamps or tungsten incandescent lamps.
The conventional structure of LED lamps can be found in prior art. For instance, R.O.C. patent Nos. M358239 and M356835 and FIG. 1 disclose the conventional LED lamps. As shown in FIG. 1, it has a base 100, a shell 101 connecting to the base 100 and a LED 102 held in the shell 101. The shell 101 usually is made from the plastic material. To facilitate mold releasing during production of the shell 101, a larger opening has to be formed on the shell 101 to connect to the base 100. This results in a weaker structural strength of the shell 101 that is not able to withstand a greater stress. Hence the shell 101 is easily fractured or shattered when subject to external impact. It does not fully meet safety requirements and has safety concern when in use. Moreover, the LED 102 could continuously emit strong light even if the shell 101 is broken away or shattered, it is irritating to user's eyes and repulsive.
To solve the aforesaid problem, techniques to increase the structural strength have been proposed. For instance, R.O.C. patent No. M317651 discloses a technique which is similar to FIG. 2. It also has a base 200, a shell 201 connecting to the base 200 and a LED lamp 202 held in the shell 201. It differs from the previously technique by having a smaller opening on the shell 201 to connect to the base 200 and can withstand a greater stress, thus provides a greater structural strength for the LED lamp.
The shell 201 shown in FIG. 2 also is made from the plastic material. In order to form the shell 201 with a smaller opening without affecting mold release, the space formed inside to hold the LED has to be uniform in diameter and smaller than the opening. This results in that the shell 201 usually has to be formed at a greater thickness, especially for a round-shaped shell 201. This also results in light penetration deficiency, and a greater number of LED 202 is needed to enhance the lighting brightness. As a result, energy consumption increases, and more plastic material is needed to make the shell 201 and production cost is higher.